What type of doors can allow return air to travel through the living space?

Undercut doors are specifically designed to allow air to flow underneath the door and into the space beyond. By having a slight gap at the bottom, these doors facilitate the movement of return air from the living space back into the HVAC system. This is essential for maintaining balanced air pressure and ensuring adequate circulation throughout the building.

In contrast, solid doors and metal doors typically create a complete seal when closed, which can inhibit air movement and disrupt the efficiency of the HVAC system. Sliding doors can also create barriers to airflow depending on their design, as they may not have the engineered gap that an undercut offers. Thus, undercut doors are the best choice for promoting effective air return in a living space.